Connector for point initiating to base detonating projectile



June 6, 1961 CONNECTOR N. A. voss ET AL 0 2,987,000 FOR POINT INITIATINGTO BASE DETONATING PROJECTILE Filed April 15, 1960 INVENTORS NED A. VOSSBY WILLIAM F KAUFMANNJR. X mm JQ Q JW ATTORNEYS:

United States Patent 2,987,000 CONNECTOR FOR POINT INITIATING T BASEDETONATING PROJECTILE Ned A. Voss, York, and William F. Kaufmann, Jr.,Philadelphia, Pa., assignors to the United States of America asrepresented by the Secretary of the Army Filed Apr. 13, 1960, Ser. No.22,065 3 Claims. (Cl. 102-70) (Granted under Title 35, U.S. Code (1952),sec. 266) The invention described herein may be manufactured and used byor for the Government for governmental purposes without the payment tous of any royalty thereon.

This invention relates to an explosive projectile of a point initiatingbase detonating type having a connector in the nose just behind a piezoelectric generator unit and has for an object to provide a projectile ofthis type better adapted to withstand higher muzzle accelerationswithout rupture of the electric circuit connections between the nose andbase under the higher stresses created during set back.

In projectiles for guns of a size between about 76 to 120 millimeters,efforts have been made to increase their muzzle velocity to as much asabout 3750 feet per second. Among the many difficulties experienced weresome in the electrical connectors behind the piezoelectric crystal unitused in the point initiating to base detonating type projectiles. Whenthe increased velocity was applied to projectilesstandardized for lowervelocities it was found that in one batch slightly over 50% of them hada break occur in the electric circuit leading from the nose initiator tothe base fuze. I More specifically investigation shows a break in theconductor that was in the connector immediately behind the piezoelectric crystal unit. Another causewasfracture in the insulator body inthe same connector although in this latter situation fracture occurredin less than 50% of the previously standard rounds fired under theincreased velocity. Here again the solution was not in selecting astronger and tougher insulating material because other factors thanstrength afiect its usefulness, It was seen that an ideal solutionshould retain the old insulating material for its other advantages andretain the same size of conductor, but how to accomplish this result wasa problem. Investigation has shown that increasing the conductorstrength by making it larger was not the answer because on set back theadditional weight of the flexible conductor also increased the tensionalstress it had to withstand.

The present invention is one that has been a great improvement byeliminating the causes of fracture discovered by minute study withoutchange in size or material of which either the conductor or insulatorhad been made in order to harmonize the cures for both weaknesses. Inthe conductor, elimination of two small radius 90 bends was madepossible with satisfactory results. In the insulator it was thought thatthe stresses were too numerous and complicated. However, under thepresent invention one larger radius loop in the flexible conductorarranged in a plane generally parallel to the longitudinal axis of theprojectile and to the axis of a conductive eyelet appears to have beenthe answer to both troubles. It has involved a simplification in thenature of the stresses in the insulator body by now having that bodychiefly under compression.

Referring to the drawings:

FIG. 1 is a diagrammatic view of the projectile and the ungrounded sideof the electric circuit to which this improvement relates,

FIG. 2 is a longitudinal section through the connector on the line 2-2of FIG. 3 with the flexible conductor in position in the connector,

FIG. 3 is a right end view of the connector of FIG. 2,

re 2,987,000 Patented June 6, 1961 FIG. 4 is a section on the line 4-4of FIG. 3 but of the block alone,

FIGS. 5 and 6 are views showing a modification made of stamped metalinstead of a block.

In FIG. 1 is shown a conventional projectile 10 having in its nose acustomary piezo electric generator unit 11 from which a usual projection12 extends rearwardly into an electric connector unit 13 from whichextends a flexible conductor 14 leading to a base detonator fuze 15. Thetype and arrangement of explosive within this projectile is not shownbecause no part of this invention and the projectile elements of FIG. 1are all broadly old. The reason for FIG. 1 being shown is because thepresent improvement in the connector 13 enables the projectile topossess the new advantage of being able to be given a higher muzzlevelocity without breakage in the electric circuit between the unit 11and the detonator fuze 15. The ordinary projection 12 is splitlongitudinally tomake it yie'ldable within a metallic non-yieldableeyelet, yet adapted to make a good electrical contact.

Referring to FIG. 2 the connector 13 of this invention comprises a bodyof plastic insulating material 16 such as nylon with the usual rearcylindrical flange 17 and a recess in its forward face as shown. Withinthis recess is placed a block 18 of light weight conductive materialsuch as aluminum having therein a hole 19 extending not only through theblock 18 but also through the insulator 16 to its rear face. Theprojection 12 fits within this hole 19 and makes good electrical contactwith the metal 18 due to the expansive resiliency of this splitprojection, the outer edge 20 of this conductive recess or hole 19 isbevelled to better guide the end of projection into said hole as iscommon practice. A substantially semi-circular groove is provided inblock 18 for reception of the looped end 21 of the flexible conductor14. As shown in FIG. 2

the forward end portion of the looped conductor 14 does not extendforwardly of the front face of the insulator 16. Block 18 is made of adepth longitudinally in FIG. 2 such that the radius of curvature of theloop may be made large because otherwise it is believed the tendency forthe conductor to be broken under tension during set back and dueprincipally to the weight of the conductor wire, would be greater.

FIG. 3 shows how the sides of the wire loop may be allowed to projectbeyond the side faces of block 18 by providing small additional recessedportions of the depth of block 18. Although the laterally protrudingportions of the conductor loop in FIG. 3 are only adjacent the rear faceof block 18, nevertheless since the sides of loop 21 are passed aroundblock 18 before it is inserted in the insulator body 16, theseadditional recessed portions need to extend through the full depth ofinsulator body 16 in order that the block with the conductor in itsgroove may be inserted into the body 16 of the insulator. After passingaround block 18 the sides of the loop connected preferably by somecrimped type of connector 22 capable of withstanding tension in theconductor that is to be induced during set back when the muzzle velocityof the projectile has been raised to approximately 3750 feet per second.

In FIG. 4 the depth of the block 18 is shown as being substantially halfits width in order that the arc of curvature for the conductor groove 24in the block be substantially semicircular and thereby eliminating twoshort radius bends that were thought to have been the major factorscontributing to rupture of the conductors that were found to beincapable of withstanding the higher forces on set back incident to thehigher muzzle velocity. In that prior construction the main andsubstantially semicircular conductor loop was of smaller radius, wasaround the metal eyelet for receiving the projection (12), and was closeto and parallel to the front face of the in- 3: sulator. Such a priorconstruction is believed to have imposed fiexure and other stresses inthe eyelet and insul'ator.

FIG. 5 is a top plan view of a modified embodiment of the presentinvention in which no metal block 18 is used is cut in stamping axiallyalined with the longitudinal axis of eyelet 25. The outer edge portionof the eyelet recess is bevelled as was the case in FIGS. 2 and 3.

In both embodiments of the conductive element in the connector, one sideof the electric circuit from the piezo electric crystal is grounded tothe outer body of the projectile while the other is that throughprojection 12, connector 13, and flexible looped conductor 14 to thebase fuze 15. The exact reasons why this connector, its insulating bodywith its conductive parts are better able to withstand the forces set upduring set back are not fully understood perhaps because the stresses inthat prior standardized construction were more complex. This improvementhas been proven superior to the old without any increase in size orstrength of its parts and the inherent weakness as in both the insulator16 and conductor 14 have at the same time been largely eliminated.

. 4 r through said projection, connector, and conductor, said conductorhaving a loop formed therein and extending into said connector, acentral metal eyelet in said connector recess into which said projectionis received, and an insulator in said connector for positioning saideyelet and loop in said projectile, the combination therewith of theimprovement enabling said projectile to be subjected to muzzle velocityof about 3750 feet per second and stress in said conductor from set backwith reduced danger of rupture of said conductor and insulator, saidimprovement including said conductor loop being within said insulator ina plane generally parallel to a longitudinal axis of said eyelet andprojectile, and a conductive strip between said loop and insulator andalso being laterally between said eyelet and loop, whereby said loop maybe semicircular within said insulator, given a radius of curvature aboutequal to the longitudinal depth of said insulator and said conductor befree of any smaller radius bends than that in said loop and whereby saidinsulator is subjected to compression under said loop.

2. A combination according to claim 1 in which said conductor eyelet andloop support is a block of metal fitting said insulator and having agroove formed therein for positioning said loop.

3. A combination according to claim 1 in which said eyelet and loopsupport are a unitary structure and formed from sheet metal.

References Cited in the file of this patent UNITED STATES PATENTS1,511,622 Lucas Oct. 14, 1924 2,633,800 Cagle Apr. 7, 1953 2,754,756Duesing July 17, 1956 2,764,091 Hudson Sept. 25, 1956 2,827,851 FarraraMar. 25, 1958 2,834,292 Viasmensky May 13, 1958 2,849,957 Kuller Sept.2, 1958 2,894,457 Severance July 14, 1959

